Study and Application of Polarographic Catalytic Wave of Chlordiazepoxide in the Presence of Persulfate

Abstract

AbstractPolarographic catalytic wave of chlordiazepoxide in the presence of K2S2O8 was studied in aqueous and DMF/H2O mixed solutions. The results showed that a single reduction wave in alkaline medium was the reduction of the N = C bond in 1,2‐position of chlordiazepoxide via an intermediate free radical in two one‐electron successive additions. When K2S2O8 was present, the free radical of the N = C bond was oxidized to regenerate the original, producing a parallel catalytic wave of chlordiazepoxide. It was determined that the apparent rate constant kf of the oxidation reaction was 3.2 × 103 mol−1·L·s−1. Using the catalytic wave the trace of chlordiazepoxide can be determined by linear‐potential scan polarography. In NH3/NH4Cl (pH 10.2 ± 0.1, 0.12 mol/L)/K2S2O8(0.016 mol/L) supporting electrolyte, the second‐order derivative peak current of the catalytic wave was rectilinear to chlordiazepoxide concentration in the range of 3.20 × 10−8‐1.60 × 10−7, 1.60 × 10−7‐1.44×10−6 and 1.44×10−6‐1.44x 10−5 mol/L, respectively. The limit of detection was 9.0×10−9 mol/L.